The present invention relates to a new method for suppressing chemical substance craving comprising electrical stimulation of the spinal cord using one or more implantable leads containing at least two conducting electrodes. The method may be used to suppress craving for alcohol, narcotics, cocaine and amphetamines. The method is particularly suited to the suppression of nicotine craving.
Tobacco related deaths are the largest single cause of premature death in developed countries. More than 400,000 deaths per year are linked to smoking related illness in the U.S. alone. However, despite the well publicized risks and consequences associated with tobacco use, more than 25% of adults in the United States continue to smoke with prevalence rates varying according to demographics.
The benefits of smoking cessation are substantial. Immediate benefits accrue to smokers who quit, including those with smoking-related disease. The risk of disease declines with smoking cessation and continues to drop through periods of abstinence. After 10-15 years of abstinence, mortality risks are equal to those of non-smokers. Smoking cessation decreases the risk of stroke, aortic aneurysm, peripheral vascular disease and myocardial reinfarction in individuals with myocardial infarction. Similar risk reduction exists in the incidence of smoking related cancers, chronic obstructive pulmonary disease and pregnancy related complications. An effective treatment for smoking addiction would result in a significant public health advance.
Previous attempts to effect smoking cessation can be divided into two categories, non-pharmacologic interventions and pharmacologic interventions. Non-pharmacologic interventions focus on altering the behavioral conditioning of smokers so that smoking is avoided or is a disfavored activity. Pharmacologic interventions are geared toward lessening the craving for nicotine and are divided into the current mainstay, nicotine replacement therapy (the only pharmacologic therapy with FDA approval) and other forms of drug therapy. The patented pharmacologic therapies employ transdermal azapirones (U.S. Pat. Nos. 5,837,280; 5,817,679; 5,633,009), nicotine receptor agonists and antagonists (U.S. Pat. Nos. 5,817,331; 5,691,365), nicotine lozenge (U.S. Pat. Nos. 5,662,920; 5,549,906), cotinine (U.S. Pat. No. 5,612,357), transdermal nicotine systems including subsaturated prolonged activity patches (U.S. Pat. Nos. 5,004,610; 4,839,174), and methods for anticholinergic blockage of withdrawal symptoms (U.S. Pat. No. 4,555,397). Unfortunately, as discussed below, none of the varied therapies, whether used singly or in combination, are very effective.
The effectiveness of various methods for smoking cessation was studied and reported in a large meta-analysis derived from 188 randomized controlled trials evaluating multiple interventions intended for smoking cessation (See Law, M. An Analysis of the Effectiveness of Interventions Intended to Help People Stop Smoking. Archives Internal Medicine. 1995; 155:1933-1941). In the meta-analysis, previously investigated interventions were evaluated and their outcomes given.
The meta-analysis found that even the most effective therapies (nicotine replacement) showed a marginal success rate of 13%. No other therapy or therapies in combination showed success rates of greater than 5% except in the rare instance of special risk groups (pregnant women, patients with ischemic heart disease or previous myocardial infarction) who exhibited up to an 8% quit rate when given advice and encouragement to quit based on their special risk. Non-pharmacologic therapies fared poorly with the success rates no greater than that achieved with physician advice. More recently, a Mar. 2, 1999 New York Times article indicated new success using a combination therapy with sustained buproprion, nicotine replacement and counseling, citing an Oct. 23, 1997 article in the New England Journal of Medicine (Vol. 337, No. 17, pg. 1195). However, despite initial promise, one year follow-up cessation rates were 24.4% at the highest buproprion dose compared to 10.5% cessation rate for placebo. This rate advantage over placebo was consistent with the poor success rate using other methods. These low success rates illustrate the limitations and failures of the prior interventions and highlight the need for improved treatments to effect smoking cessation.
Clearly, there exists a real need in the art for effective therapies and specifically more effective non-pharmacologic therapies in the treatment of nicotine addiction. There is also a need in the art to develop non-pharmacologic therapies for the treatment of addictions to other chemical substances such as alcohol, narcotics, cocaine and amphetamines.